Miklowitz et al. (2016) have explored this question in a small sample, where they examined circulating levels of inflammatory cytokines as well as spontaneous and stimulated levels of activated nuclear factor kappa B (NF-κB) in total peripheral blood in 18 adolescents with BD, 13 with MDD, and 20 without a history of psychiatric disorders. Here, NFKB1 is linked to major depressive disorder.